Perforation burr elimination



Jan. ilwi W43. R, E. HENDRICKSON 2,303,006

PERFORATION BURR ELIMINATION Filed Aug. 4, 1941 INVENTOR 1644/ E flame/arm ATT R 'atenteg am 12, 1943 2,308,006 rnnronarron Bonn ATION Ralph E. Hendrickson, Glendale, cane, assignor to Lane-Wells Company, Les corporation of Delaware Angeles, Calif., a

Application August 4, muse-m No. 405,359

(01. rel-as) 6 Claims.

My invention relates to a means and method of eliminating the burrs which are formed on the inside of well casing when gun-perforated; that is, when pierced by bullets fired from gun perforators. Among the objects of my invention are:

First, to provide a means and method of this character wherein the burr normally formed on the inside wall of a well casing due to the discharge of a gun perforator bullet therethrough is either eliminated entirely or reduced to a minimum so as to leave the interior of the casing smooth, whereby swabbing tools or other well devices may be safely moved along the interior of the casing without danger of being cut or torn, or damaged by the burr;

Second, to provide a means and method of this character which may be incorporated in a conventio perforator: and

T, to provide a means and method of this character wherein a mass of soft material surrounds the bullet as it penetrates the casing, the soft material being maintained under pressure so that burrs cannot be raised from the inner surface of the casing.

' With the above and other objects in view, as may appear hereinafter, reference is directed to the accompanying drawing, in which:

Figure 1 is a sectional view of a gun barrel shown by fragmentary section with a bullet therein, and illustrating one form of my device for eliminating burrs;

Figure 2 is a view of the bullet, casing and burr-eliminating means as it is believed they appear during'the course of penetrating the casing with the bullet; and V,

Figure 3 is a sectional view similar to Figure 2, showing the casing as it appears after being pierced by the bullet, Figure 3 being a drawing made directly from a casing section actually pierced by a bullet utilizing my method and device;

Figure 4 is a view similar to Figure 1, showing a modified form of my device;

Figure 5 is another view similar to Figures 1 and 4, showing a further modified form of my device:

Figure 6 is another longitudinal sectional view of a gun perforator barrel, showing a bullet and r a further modified form ofmy device;

Figure '1 is a still further modified arrangement of my device, shown in association with a gun perforator bullet; and

Figure 8 is a longitudinal sectional view of a well casing taken through a perforation made by a conventional gun perforator in which no means is provided for eliminating the burr, so as to illustrate the typical casing burr which is eliminated by my device and method.

My method of eliminating the burr otherwise occurring on .the inside of well casings as the result of gun perforating consists essentially in providing a relatively soft plug of metal positioned in the gun bore ahead of the bullet. The plug of metal has sumcient mass to form a ring around the bullet as it penetrates the well casing. The plug is impaled by the bullet and held in position by the explosive blast following the bullet, so that a burr which would otherwise form on the inside of the casing is prevented from forming.

With reference to Figure 1, a gun bore l is shown having a sealing cap 2 over its outer end, to which is soldered or otherwise secured a plug 3 having a recess 0 in its inner end substantially conforming to the point of a bullet 5 shown in the gun barrel. The plug 3 is formed of any relatively soft malleable material such as brass, aluminum, lead or various alloys of these metals.

The sealing cap 2 serves to exclude water from the gun barrel. In operation, the bullet strikes the plug and apparently carries the plug on its pointed end, impaling it against the inside of the casing 6, as shown in Figure 2. The bullet continues on through the casing 5 to form a perforation ll.

A construction substantially as shown in Figure 1 has been actually used to penetrate casing and the resulting perforation, indicated by 1, appears as shown in Figure 3. Traces of the plug 3 which, in tests, was formed of brass, could be seen along the walls of the perforation 1. Actually, the bullet was caused to penetrate in succession several thicknesses of casing spaced from each other, and traces of the metal from the plug were found along the walls of each perforation. It is apparent, therefore, that the plug serves an additional purpose, namely, as a lubricant for the bullet. The brass plug either disintegrates or is broken into small particles which do no harm.

The sealing cap 2 shown in Figure 1 is the type shown inthe Turechek Patent No. 2,092 ,294. However, the type of sealing disk such as shown in the Turech'ek Patent No. 2,216,144 may be employed in conjunction with the plug;' this is shown in Figure 4, in which a. cup-shaped seal disk H is shown in the end of the gun barrel I and a plug I2 is shown soldered thereto at its central portion. Clearance is provided around the marginof the plug and the seal disk in order that the seal disk H may fit in place.

Reference is now directedto Figure 5, in which, in place of the seal disk 2 or II. a seal plug 2| is shown. This comprises a minor diametered portion 22 which fits within the gun bore and a major diameter-ed portion 28 which fits in a counterbore at the outer end of the gun bore. A gasket 24 may be provided between the confronting shoulders of the plug 2| and the counterbore. The plug 2| is formed of soft material and may be provided with a socket 4 such as shown in Figures 1 and 4', or may be solid.

Reference is now made to Figure 6: In this construction the gun bore I is shown lined by a soft metal tube 3| which is preferably pressfltted into the bore l for the purpose of holding the bullet at the inner end thereof until the bullet is driven from the barrel by'ignition of the gun perforator cartridge (not shown). The liner or tube 2| is, of course, of suiilciently soft material'that it will upset to form, at the time the bullet pierces the casing, an annular mass or ring such as illustrated in Figure 2;

Reference is now directed to Figure '7: In this construction a plug 4|, similar to plugs 8 and I2 and having a socket 42, is fitted directly on the pointed end of the bullet instead of the cap 2 or II.

While it is impossible to ascertain just what happens to the plug and bullet and the casing as the perforation is being made, the results of actual experiments have shown that the presence of the soft plug ahead of the bullet does prevent or reduce materially the formation of burrs on the inside of the well casing. In some instances very slight burrs were formed, but these were rounded and not sharp and jagged. In contrast to this, the burr formed by a conventional gun perforator bullet is shown in Figure 8, in which a ragged, sharp, internal burr 5| is formed on the inner side of the perforation 52 found in a casing 53. In many instances these burrs are highly objectionable. They damage many well toolsthat are lowered through a gunperforated casing, particularly swabbing tools which have swabbing rubbers designed to bear against the walls of the casing, or packers having packing rings designed to seal against the casing.

Various changes and alternate arrangements may be made within the scope of the appended claims, in which it is my intention to claim all novelty inherent in the invention as broadly as the prior art permits.

Iclaim:

1. In a gun perforator, the combination with a gun unit having a gun bore and a pointed bullet, of: a mass of relatively soft metal having a central bore adapted to receive the point of the bullet, said bore extending at least part way through said seasons mass, said mass seed in the gun bore in from of the bullet, said mass adapted to be carried b: the bullet against a surrounding casing and b deformed by the bullet into a collar surroundim thebullet during penetration of the casing t minimize formation of burrs on the interior of thi casing.

2. A method of mlnlmizingthe formation 0. burrs on the inside walls of well casing durim penetration of a bullet therein, characterized by; initially positioning a mass of relatively soft meta ahead of a bullet; driving the mass against thi casing by the bullet and holding the mass againsi the casing while the bullet penetrates the mas: and the casing.

3. In a gun perforator, the combination with a gun unit having a gun bore and a bullet, of: a mass of relatively soft material having lubricating properties, positioned ahead of the bullet whereby the mass is driven by the bullet against a surrounding casing and impaled thereby as the bullet penetrates the casing to restrain the formation of burrs on the interior of the casing, and lubricate the bullet as it passes therethrough.

4. In a gun perforator, the combination with a gun unit having a gun bore and a pointed bullet, of: a plug of relatively soft material disposed at the muzzle end of said gun bor and having a socket for receiving the pointed end of the bullet as it discharges from the gun unit, said plug adapted to be impaled by the bullet as the bullet penetrates a surrounding casing, and said plu having sufllcient mass to restrain the formation of burrs around the interior end of the opening made in the casing by the bullet.

5. In a gun perforator, the combination with a gun unit having a gun bore and a bullet, of: a plug of relatively soft material initially secured to and covering the outer end of the bullet and adapted to be carried by the bullet as it discharges from the gun unit, said plug adapted to be impaled by the bullet asthe bullet penetrates a surrounding casing, and said plug having suflicient mass to restrain the formation of burrs around the interior end of the opening made in the casing by the bullet.

6. In a gun perforator the combination with a gun unit having a gun bore and a pointed bullet, of: a liner of relatively soft material fitted in the gun bore ahead of said bullet, said liner adapted to be forced from said bore by the bullet and tending to crush into a collar surrounding the bullet as the bullet engages and penetrates a surrounding casing, said liner having sumcient mass to restrain the formation of burrs around the interior end of the opening made in the casing by the bullet.

RALPH E. HENDRICKSON. 

